Quantitative chemistry


Volume Calculations

Volume of gas in dm3:

moles = volume/24

n = V/24

Volume of gas in dm3:

Volume = Mass x 24


V = (m/Mr) x 24


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Concentration Calculations

Concentration of solution in mol/dm3:

concentration1 x volume1 = concentration2 x volume2

   moles1                                  moles2

Concentration of solution in mol/dm3:

moles = concentration x volume


Concentration of solution in g/dm3:

mass = concentration x volume

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Percentage yield:

% yield =        Actual mass x 100

                      Theoretical mass

Atom Economy:

Atom economy = ΣAr Desired Product x 100

                                  ΣAr Reactants


Uncertainty = Range/2

% Composition of an element:


% = 100 x (Ar x No element)


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Relative atomic mass:

Ar = Ʃ(Mass number x abundance)

                   Total abundance

Relative formula mass:

Mr = ∑(Ar x number of atoms)

Law of conservation of mass:

Total mass  =  Total mass

of products     of reactants

Mass of solid in grams:

moles = mass/Mr

n = m/Mr

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In chemistry, amounts of substances are measured in moles.

One mole of any substance is just the amount of that substance that contains an Avagadro number of particles - so 6.02 x 10^23 particles.

The mass of one mole of atoms or molecules of any substance is exactly the same number of grams as the relative atomic mass or relative formula mass.

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Limiting Reactants

The reaction stops when all of one of the reactants is used up.

Any other reactants are in excess.

They're usually added in excess to make sure that the other reactant is completely used up. The reactant that's used up in a reaction is called the limiting reactant (because it limits the amount of product that's formed). 

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